High-energy-density electrical storage devices as typified by lithium ion secondary batteries, lithium ion capacitors, and electric double layer capacitors include, for example, an electrical storage device (laminated electrical storage device) that has a structure such that a laminate case composed of laminate films (for example, laminate films of aluminum foil sandwiched between thermoplastic resin layers) houses therein an electric storage element configured in such a way that sheet-like positive electrode members and negative electrode members formed by coating sheet-like current collecting foil (aluminum foil or copper foil) with active materials (such as activated carbon, lithium composite oxide, or carbon) are laminated with separators interposed therebetween for preventing short circuits due to both the members in contact with each other; and an electrolyte.
Now, as one of these electrical storage devices, there is a battery (laminated battery) that has a structure such that as schematically shown in FIG. 6, a battery element 101 is housed in a laminate case 102 composed of laminate films 102a, 102b, and external terminals 103 (positive electrode terminal 103a and negative electrode terminal 103b) connected through current collecting members 105 to the battery element 101 are extended externally from the laminate case 102.
In this battery, the laminate films 102a, 102b constituting the laminate case 102 are welded to the external terminals 103 to seal portions of the laminate case 102 from which the external terminals 103 are extended.
Further, as a method for sealing the portions of the laminate case from which the external terminals 103 are extended in the case of manufacturing such a battery, Patent Document 1 represents, for example, as shown in FIG. 7, a method of, in welding laminate films 181 of thermoplastic resin constituting a battery case 180 and the external terminals 130, pressing heating means 205, 206 against both the front and back surfaces of ends of the external terminals 130 to pre-warm sealants 191 of thermoplastic resin through the external terminals 130, and then pressing heated pressing jigs 201, 202 against both the front and back surfaces of ends of the battery case 180 to heat-seal the laminate films 181 to the external terminals 130 with the sealants 191 interposed therebetween, thereby sealing extensions of the external terminals 130 from a battery case 180.
However, in the case of this method, because the heating means (heat sources) are pressed against the external terminals, the external terminals may be damaged, or the external terminals against which the heating means (heat sources) are pressed may move to decrease the reliability of sealing the battery case with the sealants or damage members (for example, current collecting foil for positive electrodes or negative electrodes) connected to the other ends (the inner sides of the laminate case) of the external terminals.
In addition, Patent Document 2 represents a method (hot air method) of blowing hot air to preheat heat-sealing materials provided to cover predetermined regions of lead terminals, thereby shortening the time required for integrally heat-sealing sealant layers of laminate films and the heat-sealing materials of the lead terminals.
However, the hot air method may heat and damage members constituting batteries, such as separators because the hot air is extensively blown. Moreover, in the case of the hot air method, a heat source of heating pressure bonding means for thermocompression bonding and a heat source for heating air are required separately, thereby resulting in the problem of causing an increase in equipment cost or running cost.
Patent Document 1: Japanese Patent Application Laid-Open No. 2009-272161
Patent Document 1: Japanese Patent Application Laid-Open No. 11-312514